Human nerve cells grown from scratch

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A team of scientists, based in Australia, has grown human nerve cells in the lab, in the first successful attempt to control the development of embryonic stem cells. Their work is a major step towards the production of replacement tissues for treating neurodegenerative conditions like Parkinson's and Alzheimer's disease.

Researchers worldwide have been in heavy competition over the past few years to capture the potential of embryonic stem cells - a kind of 'template' cell - by directing their differentiation into a specialised cell such as a nerve or muscle cell. The Melbourne-based team, headed by Dr Martin Pera at Monash University's Institute of Reproduction and Development together with colleagues in Israel and Singapore, is the first to succeed. Their results are reported in this week's issue of Nature Biotechnology.

The announcement has rekindled ethical debate about using human embryos as the source of stem cells, with the Right to Life movement describing the research as "biological cannibalism".

Great hope has been placed in stem cells because their ability to grow into any type of cell means they could be used to develop new tissues for disease treatment, and possibly organs for transplantation. If nerve cells can be grown from scratch in the lab, for example, they may eventually be able to be injected into the brains of people with Alzheimer's disease to replace degenerating tissue.

"Because human embryonic stem cells represent, in principle, an indefinitely renewable source of any type of human cell, they have major applications in research and medicine," said Monash team member Professor Alan Trounson.

However, much is yet to be learned about the basic mechanisms of stem cell development - the molecular 'instructions' that direct a cell to become one type or another.

"It must be noted that almost all of the wide-ranging potential applications of [embryonic stem] cell technology in human medicine are based on the assumption that it will be possible to grow [embryonic stem] cells on a large scale, to introduce genetic modifications into them, and to direct their differentiation," the researchers wrote. Their success in maintaining stem cell lines in culture for an extended period, isolating early-stage nerve cells and nurturing them into mature nerve cells, is an important demonstration that the speculative potential of stem cells can actually be harnessed in practice.

The ethical dilemmas in stem cell research arise from the use of cells from human embryos (such as unwanted embryos donated by parents from in-vitro fertilisation programs) to get the cell lines started. Because current Australian guidelines restrict the use of such cells, the Monash team used cell lines imported from Singapore.